Davis Instruments Fan-Aspirated Radiation Shield User manual

Product#7750,7751,7752,7755,7756&7757
F
AN
-A
SPIRATED
R
ADIATION
S
HIELD
I
NSTALLATION
M
ANUAL
(For all models with Mfg. Code
beginning with B or higher)
The Fan-Aspirated Radiation Shield uses fan aspiration and passive shielding
to minimize the effects of solar radiation and to provide accurate temperature
readings. This instruction manual takes you step-by-step through the process
of installing and mounting your Fan-Aspirated Radiation Shield.
Note: Installation varies according to the shield type, so please take note of your product number before
you begin to install. You can find the model number on the label on the underside of the Fan Plate.
Components
The Fan-Aspirated Radiation Shield includes these items:
#8 Hex Nuts (3)
#4 Self-Threading Screws (4)
Battery Covers (2)
1.2 Volt Nicad Batteries (2)
O-Rings (2)
#8 Lock Washers (3)
#8 Flat Washers (3)
Mounting Bracket
with Solar Panel
SOLAR MODELS
7755, 7756, 7757
ONLY
SOLAR MODELS 7755, 7756, 7757 ONLY
Mounting Bracket
AC MODELS
7750, 7751, 7752
ONLY
3 Volt
Power Adapter
AC MODELS
7750, 7751, 7752
ONLY
Industrial
Sensor Cable,
16 feet (4.9 meters)
MODELS 7752, 7757
ONLY
Standard
Sensor Cable,
40 feet (12 meters)
MODELS 7751, 7756
ONLY
Fan-Aspirated
Radiation Shield
Junction Board Cover
#4 x 1/2" Screw
#4 Flat Washer
Cable Clamp

Page2 Fan-AspiratedRadiationShield
A Note About Model Versions
This manual is for all versions of the Fan-Aspirated Radiation Shield manufac-
tured after 9/1/01. Earlier versions have the following differences:
✦
Solar-powered modules only use one battery versus two batteries
✦
All Junction Board-connections are soldered versus using connectors
Aside from those differences, the installation of the early versions of the
Fan-Aspirated Radiation Shield is the same as for current versions.
Tools and Materials Needed
To disassemble, install, and mount your Fan-Aspirated Radiation Shield, you
may need the following:
✦ A medium Phillips-Head screwdriver.
✦
A small Phillips-Head screwdriver.
To install an existing Davis Temperature/Humidity sensor.
✦
A small wrench or 3/8” (9 mm) nutdriver.
✦
A radiation shield bracket (#7994).
To mount the radiation shield on a mast or pipe if you wish.
Installation Steps
The Fan-Aspirated Radiation Shield comes pre-assembled. Depending on your
model number, you may need to disassemble your shield to install a battery
and/or a sensor or probe. Here are the installation steps for each shield.
M
ODEL
7750 M
ODELS
7751 & 7752 M
ODEL
7755 M
ODELS
7756 & 7757
1.Disassembletheshield
Page3 1.Disassembletheshield Page3 1.Disassembletheshield Page3 1.Disassembletheshield Page3
2.Installasensororprobe
Page4 2.Powerthefan Page8 2.Installasensororprobe Page4 2.Powerthefan Page8
3.Installthesensorboard
Page6 3.Reassembletheshield Page12 3.Installthesensorboard Page6 3.Reassembletheshield Page12
4.Powerthefan
Page8 4.Mounttheshield Page15 4.Powerthefan Page8 4.Mounttheshield Page13
5.Routethecables
Page10 5.Routethecables Page10
6.Reassembletheshield
Page12 6.Reassembletheshield Page12
7.Mounttheshield
Page15 7.Mounttheshield Page15

DisassemblingtheRadiationShield Page3
Disassembling the Radiation Shield
Use a medium Phillips-Head screwdriver to disassemble as described below:
1. Unscrew the three screws at the top of the unit and remove the mounting
bracket.
2. Remove the two plates and put aside.
3. Gently remove the fan and the deflector, taking care not to stress the wires
soldered to the terminal board.
4. Slide out the sensor board.
5. You are now ready to install a sensor or probe. (See page 5.)
Disassembling the Shield
Mounting Bracket
with Solar Panel
SOLAR MODELS
Mounting
Bracket
AC MODELS
2" Screws (3)
Lock Washers
Flat Washers
Closed Plate
(no hole in center)
Open Plate
(hole in center)
Fan Unit
Core Unit
Solar Power Cable
SOLAR MODELS
Sensor Board
with Temp Probe
T
emp/Humidity Sensor
F
ACTORY INSTALLED
N
MODELS 7751, 7752,
7756, AND 7757;
DO NOT REMOVE)
Motor
Connector
Fan Plate
Battery Compartment
Baffles
Air Inlet (underneath)
Fan Deflector
Power Cable
AC MODELS

Page4 Fan-AspiratedRadiationShield
Installing a Sensor or Probe
For models without a pre-installed sensor, continue to the section “To install a
sensor or probe on the sensor board.” (See below).
If you want to install your own Davis Temperature/Humidity sensor (#7859 or
#7860), you must remove your old sensor housing and attach a new and
smaller sensor board cover. Please continue to the section “To attach a new
sensor board cover.” (See below.)
To install a sensor or probe on the sensor board:
1. Attach the sensor or probe to the board using the cable ties.
2. You are now ready to install the sensor board. (See page 6.)
To attach a new sensor board cover:
If you have an existing Temperature/Humidity sensor model # 7859 or # 7860,
you need to attach a new sensor cover as follows:
1. Remove the shell and main cover by removing the screw at the front of the
board beside the cable exit point.
2. Remove the warranty label on the back of the cover and undo the screw.
Note: Removing this warranty label to attach a new sensor board does not void your warranty in this
instance. To avoid damaging sensitive components on the PC board, hold the board by the edges.
Sensor
Board
Davis
Temp Probe
Cable Ties
(2 places) Sensor
Board
Vaisala
Temp Probe
Cable Ties
(2 places)
Installing a Sensor or Probe on the Sensor Board

InstallingaSensororProbe Page5
3. Remove the sensor board and discard the “old” cover and shell.
4. Fit the new sensor cover on the front of the sensor board as shown below.
5. Insert and tighten the #4 x 3/8” (9.5 mm) screw in the back of the sensor
board.
6. You are now ready to install the sensor board.
Main
Cover
Sensor
Board
Base
#4 x 3/8"
Screw
#4 x 3/8"
Screw
#4 x 3/8"
Screw
Shell
Removing the “Old” Temp/Hum Housing
Sensor
Cover
Board removed from
Davis #7859 or #7860
Temp/Humidity
Sensor
#4 x 3/8"
Screw
Attaching a New Sensor Board Cover

Page6 Fan-AspiratedRadiationShield
Installing the Sensor Board
Here’s how to install the sensor board supplied with the radiation shield:
1. Insert the board into the grooves in the sensor chamber walls.
2. Push the cable gently into the sensor chamber, allowing the cable to loop a
little.
3. Route the cable to the cable channel.
Core Unit
Sensor
Chamber
Cable
Channel
Temp/Humidity
Sensor Board
with
Sensor Cover
Temp Probe
mounted on
Sensor Board
OR
Installing the Sensor Board

InstallingtheFan Page7
Installing the Fan
Here’s how to install the fan:
1. Install the fan deflector, ensuring that the sensor cable is in the cable chan-
nel molded into the fan deflector and the fan plate.
2. Place the fan unit on top of the deflector.
3. Connect the motor power cable to the Motor Connector on the Junction
Board.
Fan Unit
Fan Deflector
Motor Connector
Junction Board
Fan Plate
Installing the Fan

Page8 Fan-AspiratedRadiationShield
Powering the Fan
AC-powered models are powered by an AC-power adapter. Solar-powered
models have a solar power panel and use batteries for overnight power. Refer
to the Junction Board Connections illustration when powering the fan.
AC-Powered Radiation Shield
1. Locate the Junction Board on the fan plate (See page 7).
2. Connect the AC-power adapter to the +5V connector on the Junction Board.
3. Plug the AC-power adapter into an AC outlet.
4. Check to see that the fan is blowing air up and away from the sensor.
5. Unplug the AC power adapter from the AC outlet until you have finished
mounting the radiation shield.
6. Secure the AC power cable to the fan plate with the supplied cable clamp.
7. You are now ready to route the cables.
MOTOR
+VSOL
+5V TACH
Solar Power Connector
(Solar-Powered Models Only) Motor Connector For Future
Tachometer
AC Power Adapter Connector
(AC-Powered Models Only)
Junction Board Connections
Junction
Board
AC Power-Adapter Connections

InstallingtheFan Page9
Solar Powered Radiation Shield
The solar-powered fan will begin operating as soon as you install the batteries.
To prevent discharging the batteries, only install the batteries immediately
before you mount the radiation shield.
1. On the Radiation Shield fan plate, insert the O-ring in the groove around
the edge of each battery compartment.
2. Insert a NiCad battery in each compartment, matching the plus (+) sign on
the battery with the plus (+) sign in the battery compartment.
3. Verify that the fan is blowing air up and away from the sensor.
4. Attach the battery covers to the battery compartments using two #4 x 3/8”
(9.5 mm) screws each.
5. You are now ready to route the cables.
#4 Screws
Battery Cover
1.2 Volt Nicad
Battery
O-Ring
Battery
Compartment
Installing the Batteries
(Solar-Powered Models Only)

Page10 Fan-AspiratedRadiationShield
Routing the Sensor and Power Cables
To route the cables do the following:
1. Loosen the cable clamp screws on the top of the unit core, remove the cable
clamps.
2. Route the sensor cable and AC or solar power cable through the clamp.
3. Secure the clamp to the unit using the screw provided.
4. Connect the sensor cable to the appropriate connector on the junction
box/sensor interface. Consult your station installation manual for more
information.
5. For AC-powered models, route the power-adpater cable to an AC outlet
AC Cable Routing
#4 x 1/2" Screw
#4 Flat Washer
Cable Clamp
Power Adapter
Cable
Battery
Compartments
(not used in
AC Models)
Fan Motor
Sensor Cable
Fan Plate
Junction
Board
Use Cable Clamp to
Attach Cables